Are you sure that the temperature and humidity have been correct during the hatch? If so, you need to candle the eggs. Even though you have been told not to open the incubator during lockdown, it is ok to open it to candle eggs if they have not externally pipped, as long as you close it right away and make sure the humidity stays where it should be.
If the temperature was too low or if you did not count the days right (the first day is day 0, so day 21 would be the same day of the week , three weeks after you set the eggs, you may give them another day, but in the meantime you may need to start reading the assisted hatching guide in this forum.